The present invention relates to a process for preparing fatty alcohols, in which a stream comprising at least one fatty acid triglyceride is provided and this stream is subjected to a hydrogenation in the presence of a heterogeneous copper catalyst.
Fatty alcohols are important intermediates for a multitude of chemical products, for example surfactants and cosmetic products. They can be prepared, for example, by hydrogenating fatty acid methyl esters, which are obtainable from fatty or oily starting materials by transesterifying the triglycerides present. A further product of value obtained is glycerol, which can be subjected, for example, to a hydrogenation to obtain 1,2-propanediol.
It is known that the hydrogenation of glycerol to prepare 1,2-propanediol can be performed in the presence of heterogeneous copper catalysts. Such processes are described, for example, in WO 2007/099161, WO 2009/027500, WO 2009/027501 and WO 2009/027502.
It is also known that fatty alcohols can be prepared by direct hydrogenation of triglyceride-containing starting materials, for example of natural oils and fats.
DE-B 1 154 448 describes a process for preparing relatively high molecular weight mono- and polyhydric alcohols by catalytic hydrogenation of fats, fatty acids and fatty acid esters using tableted copper-zinc, copper-chromium, copper-manganese, copper-zinc-chromium, copper-manganese-chromium, copper-cadmium, copper-cadmium-chromium and copper-cadmium-manganese catalysts.
EP 0 063 427 A2 describes a process for selective hydrogenation of unsaturated fatty acid derivatives in the presence of ammonia and a catalyst which comprises at least one metal selected from Pd, Pt, Ir and Rh.
EP 0 254 189 A2 describes a process for direct hydrogenation of glyceride oils in the presence of catalysts which comprise 30 to 40% by weight of copper, 23 to 30% by weight of chromium, 1 to 7% by weight of barium, based in each case on oxidic catalyst material, and if desired further transition metals in the form of oxides thereof.
DE 37 08 430 A1 describes a process for direct hydrogenation of butterfat in the presence of catalysts which comprise 30 to 40% by weight of copper, 23 to 30% by weight of chromium, 1 to 10% by weight of manganese, 1 to 10% by weight of silicon and 1 to 7% by weight of barium, based in each case on oxidic catalyst material, and if desired further transition metals in the form of oxides thereof.
DE 41 29 622 A1 describes a process for preparing unsaturated fatty alcohols by hydrogenation over a zinc-chromium catalyst of the spinel type.
DE 198 43 798 A1 describes a process for preparing fatty alcohols by hydrogenating fatty acids or fatty acid esters over a fixed catalyst bed, in which unconverted hydrogen is recovered and recycled into the hydrogenation and the reactor is cooled by sparging with unheated hydrogen.
WO 01/43873 A2 describes oxidic zinc-aluminum catalysts for the preparation of unsaturated fatty alcohols by hydrogenating unsaturated fatty acids, fatty acid lower alkyl esters or fatty acid glycerides.
US 2004/0133049 A1 describes a process for preparing fatty alcohols from fatty acids, fatty acid esters and naturally occurring triglycerides in a fixed bed reactor. Suitable hydrogenation catalysts described include oxidic copper-aluminum catalysts.
WO 96/14280 describes a process for directly hydrogenating carboxylic acids to fatty alcohols in the presence of a catalyst which comprises a copper compound, a zinc compound and at least one compound selected from compounds of aluminum, zirconium, magnesium, rare earth metals and mixtures thereof.